The present invention relates to rotary fluid pressure devices, and more particularly, to an improved lubricant system for use therein.
The present invention is particularly applicable to rotary fluid pressure devices of the gerotor type, and will be described in connection therewith. However, it should be appreciated that the invention may have broader application and may be utilized in any rotary fluid pressure device wherein torque is transmitted from one internally splined member to another such as by means of an externally splined dogbone shaft where it is desirable to maintain a constant flow of lubricant through both spline connections.
The invention is especially suited for use with hydraulic gerotor motors, a typical example of which is shown in U.S. Pat. No. 3,572,983, assigned to the assignee of the present invention. Because of the relatively low torques being transmitted from the rotor to the output shaft by the main drive shaft in such motors, lubrication of the spline connections at either end of the main drive shaft usually did not present a serious problem. However, proper lubrication of these spline connections became more important as the size and torque capability of gerotor motors increased. More recently, the torque output capability of gerotor motors was greatly increased by the development illustrated in U.S. Pat. No. 3,782,866, also assigned to the assignee of the present invention. The basis for this development was the realization that the primary factor limiting the torque output capability of the motor was the strength of the spline connection between the rotor and the main shaft and between the main shaft and the output shaft. Thus, it is now well-known in the art to provide a high torque gerotor motor utilizing an intermediate shaft, one end of which is connected to the rotor of the gerotor by a set of straight splines and the other end of which defines the relatively large set of internal splines. At the same time, the output shaft also defines a relatively large set of internal splines and a large dogbone shaft, having external splines at either end thereof, provides the main drive connection between the intermediate shaft and the output shaft. With the increased size and strength of these spline connections, the greater amount of torque being transmitted resulted in the generation of more frictional heat, as well as the creation of more wear particles. Initially, lubrication of the spline connections in hgh torque motors such as those illustrated in the referenced patent was accomplished merely by providing a lubricant sump that the external splines on the main shaft would pass through as the shaft orbited and rotated. However, this means of lubrication has not proven consistently satisfactory.